Field of the Invention
The present invention relates to a connected hot-water supply system including a connection control unit connected to a plurality of hot-water suppliers to control operation of the respective hot-water suppliers.
Description of the Related Art
Connected hot-water supply systems that use a plurality of hot-water suppliers in accordance with required hot-water supply capacity have conventionally been known (see, for example, Japanese Laid-open Patent Publication No. 2011-158138). The connected hot-water supply systems of this type, unlike large-size hot-water suppliers that are custom-designed at high cost, can be installed by connecting a plurality of general-purpose low-cost hot-water suppliers in accordance with required hot-water supply capacity. Therefore, the connected hot-water supply systems can reduce the cost of hot-water supply equipment.
When the hot-water suppliers which constitute a connected hot-water supply system are gas combustion-based suppliers including a burner, what is called a common vent system is adopted in which exhaust ducts (exhaust passages) of the respective hot-water suppliers are connected to a common exhaust duct (common exhaust passage) to collectively discharge combustion exhaust from the plurality of exhaust ducts through the single common exhaust duct. By adopting the common vent system, not only the cost of the exhaust ducts can be reduced, but also the installing space of the exhaust ducts can be reduced.
However, since a plurality of exhaust ducts of the respective hot-water suppliers are connected to a single common exhaust duct in the common vent system, a difference in pressure of the combustion exhaust among the respective exhaust ducts, if generated, may exert an adverse influence on the combustion of the respective hot-water suppliers.
More specifically, each of the hot-water suppliers that constitute the connected hot-water supply system controls the rotation speed of the fan that feeds combustion air in accordance with a combustion amount of the burner (quantity of heat in combustion of the burner, or heating capacity of the burner during combustion). Accordingly, if, for example, the combustion amount of one hot-water supplier becomes smaller than that of other hot-water suppliers while all the hot-water suppliers that constitute the connected hot-water supply system are in hot-water supply operation, the rotation speed of the fan that feeds combustion air to the burner in accordance with the combustion amount is dropped in that one hot-water supplier, which results in a drop in the pressure of combustion exhaust. In the hot-water supplier where the pressure of combustion exhaust is dropped, smooth exhausting operation is hindered due to a relatively high pressure of the combustion exhaust from other hot-water suppliers, which may increase exhalation resistance and cause combustion failure of the burner.
In view of the aforementioned point, an object of the present invention is to provide a connected hot-water supply system adopting a common vent system, which is capable of preventing combustion failure of the burner of each hot-water supplier during hot-water supply operation so as to achieve stable hot-water supply operation.